I don’t have the official dock, but the hdmi port on my dongle is able to output at 1440p@60 so I assume it can do HDR as well (can’t look it up because the dongle is unbranded and doesn’t show up online anywhere even with Google Lens). My TV isn’t hella expensive but it does have HDR10 and works with my Fire Stick 4K on HDR. The TV is an LG UR8000. Turning on HDR on the new 3.5 stable build just desaturates the image.
The specs show an 8 bit panel so it doesnt display hdr. You can check your display specs here.